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18 Cards in this Set

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Objective

List some of the more common ways that the human brain can be damaged.
The human brain can be damaged by infections, tumors, exposure to radiation or toxic substances, degenerative diseases, closed head injury, and stroke.
Objective

Compare the two types of strokes.
A stroke is a temporary loss of normal blood flow to the brain. In ischemia, a blood clot or other obstruction in an artery blocks the flow of blood to a specific brain area. Hemorrhage is the result of a ruptured artery. To use an analogy, ischemia is like a drought whereas a hemorrhage is like a flood.
Objective

Explain how strokes kill neurons.
Ischemia can starve a brain area of blood and therefore of oxygen and glucose. A hemorrhage essentially drowns the neurons in blood, flooding it with excess oxygen, calcium, and other nutrients. Both ischemia and hemorrhage result in edema (the accumulation of fluid), which can increase pressure on the brain and also the probability of subsequent strokes. Both also damage the sodium-potassium pump, leading to an accumulation of excess sodium in affected brain areas. This provokes the release of glutamates, which overstimulate the brain. Too much sodium also overwhelms the sodium-potassium pump and eventually kills the neuron.
Objective

Identify the most effective method of preventing brain damage after strokes.
The most effective method of preventing brain damage after stroke involves cooling the brain, which lowers the brain’s activity levels and energy needs. Tissue plasminogen activator (tPA) has been used to break up blood clots, and the use of cannabinoids has been shown to lower the amount of glutamate released in the affected brain areas.
Objective

Discuss five changes that can take place in the brain after a stroke.
1. Diaschesis
This is a decrease in the activity level of surviving neurons after damage to other neurons.

2. Re-growth of axons in the peripheral nervous system under the right circumstances
Axons can grow back at a rate of about one millimeter per day. In the central nervous system, axons regenerate only a millimeter or two at most.

3. Sprouting
New dendritic branches, called collateral sprouts, attach to vacant synapses.

4. Denervation supersensitivity
The surviving neurons show a heightened sensitivity to specific neurotransmitters.

5. Reorganized sensory representations and phantom limb
After a limb amputation, a remapping of sensory nerves may occur so that sensation associated with the lost limb may be felt on a remaining body part, such as the face. Some amputees experience a condition called phantom limb, in which they feel continuing sensation of an amputated body part.
closed head injury
A sharp blow to the head resulting from a fall, an automobile or motorcycle accident, an assault, or other sudden trauma that does not actually puncture the brain
stroke (cerebrovascular accident)
A temporary loss of normal blood flow to the brain
ischemia
A local blockage of blood flow in the brain caused by a blood clot or other obstruction of an artery
hemorrhage
The rupture of an artery
edema
Accumulation of fluid
tissue plasminogen activator (tPA)
Drug that breaks up blood clots and has a mixture of effects on damaged neurons
penumbra
The region that surrounds the immediate damaged area
diaschisis
Decreased activity of surviving neurons after damage to other neurons
collateral sprouts
Branches that attach to vacant synapses
denervation supersensitivity
Heightened sensitivity to a neurotransmitter after the destruction of an incoming axon
disuse supersensitivity
Heightened sensitivity as a result of inactivity by an incoming axon
phantom limb
Continuing sensation of an amputated body part
deafferented
The process of losing afferent (sensory) input